In total, the new monuments cover about 55,000 acres. Two of the protected areas — the California Coastal National Monument and Cascade-Siskiyou National Monument — are expansions of monuments designated by Bill Clinton. The other three will preserve historic sites related to Reconstruction and the Civil Rights Movement, including the hotel that once served as Martin Luther King's civil rights campaign headquarters.

Throughout his time in office, Obama has used the Antiquities Act, which Roosevelt signed into law in 1906, to set aside public land for conservation. He has ramped up those efforts as the end of his presidency draws near, furthering his administration's environmental legacy before President-elect Donald Trump takes office. In December, 2016, he created two national monuments in Utah and Nevada, covering over 1.5 million acres of land.

Added up, Obama has protected more than 550 million acres— more than double the amount that the well-known conservationist Theodore Roosevelt did. His preservation agenda has been largely applauded by environmentalists but criticized by some conservatives for placing too much land under federal control.

The majority of Obama's addition to the nation's protected acreage, however, is water — the president created and expanded several massive marine national monuments in the Atlantic and Pacific oceans (not to mention his ban on Arctic drilling).

Here's the full list, in reverse chronological order.

1/

Cascade-Siskiyou National Monument

Bureau of Land Management Oregon and Washington/Flickr

Location: Oregon and California

Size: 48,000 additional acres

Date of proclamation: Bill Clinton established the monument in June, 2000, setting aside 52,000 protected acres. On January 12, 2017, Barack Obama expanded the monument by adding roughly 42,000 acres land in Oregon and 5,000 acres in California.

2/

Birmingham Civil Rights National Monument

Library of Congress

Location: Birmingham, Alabama

Size: 0.88 acres

Date of proclamation: January 12, 2017

3/

California Coastal National Monument

blmcalifornia/Flickr

Location: California

Size: Obama first expanded the monument to include 1,665 additional acres, then later added 6,230 more acres.

Date of proclamation: Bill Clinton established the monument in January, 2000, and Obama has since expanded it two times (so it counts twice in his list of monuments created). The first expansion was on March 11, 2014, and the second on January 12, 2017.

Papahanaumokuakea Marine National Monument

Size: 582,578 square miles — the world's largest marine protected area. (The original monument was created in 2006 by President George W. Bush. Obama expanded the protected territory by 442,781 square miles.)